Process for manufacturing acid phosphate or superphosphate



. V w. T. DOYLE.

PROCESS FOR MANUFACTURING ACID PHOSPHATE 0R SUPERPHOSPHAT E.

A PPL'ICATION FILED MAR. 29. 192]- 1,40 1,527 Patented D60. 27, 1921.

2 SHEETS-SHEET I.

vent ar w. I. DOYLE. PROCESS FOR MANUFACTURING ACID PHOSPHATE 0RSUPERPHOSPHATE.

APPLICATION FILED MAR. 29, I921.

1,401,527 Patented Dec.27, 1921.

2 SHEETS-SHEET 2.

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To all whom it may mm.-

.Be it known that I, WILLIAM: Donne,

a citizen of the United States, residing at Boston, in the county of.Sufiolk and State of Massachusetts, have invented an Improve ment inProcesses for Manufacturin Acid Phosphate or Superphosphata'of which thefollowing description, in connection with the accompanying drawin s, isa specification, like characters on the rawings representing like parts.y i

This invention, relates to a process for mfiinufacturing acid phosphateor superphosp ate. One important source of this acid phosphate is in ahosphate rock which contains tribasic phosp ate of lime which isinsoluble in water, and consequently when applied to the soi1,cannot beassimilated by plants.-

To render the phosphoricacid available, it is necessar 'to convert theinsoluble hosphoric aci in phos hate rock into so uble phosphoric acid.sually this is accom plished by treating theground phosphate rock withsurfuric acid or hydrochloric acid which removes two parts of the limeas gyp-' sum and leaves one part of the lime combined with phosphoricacid asmonobasic or acid phosphate of lime soluble in water.

The ground phosphate rock and the acid, such, for example, as dilutedsulfuric acid in proportions substantially of 1,000 lbs. of

each, are thoroughly. mixed, and then discharged into a large chambergenerally built of concrete and known as a den. The mixture is allowedto stand about twelve hours in the den, which allows the chemicalreaction totake place. After a time, the mixture becomes a sponggratedor broken own and then conveyed to a curing ile where it isallowed to remain a sufficient ength of time for the chemicalreaction tocontinue and further convert insoluble phosphoric acid into solublephosphoric acid.

The above process requires feedin a batch of the mixed materials intothe en, and thenthe feed must be interrupted to permit the materials tostand in the den for the period necessary for the chemical reaction totake place. Also, the introduction of further materials into the dencannot be commenceduntil after the batch of materials has beendisintegrated and removed from the mass which is disinte-' Specificationot Letters Patent. Patented Dec, 27, 1921, Application fled mm 29, 1921.Serial No.'456,713.

. den. This, therefore, is an intermittent time consuming process.

An important aim and purpose of the present invention, therefore, is toprovide a process for the manufacture of acid phosphate orsuperphosphate, in which the ground or pulverent phosphate rock and acidmay be continuously mixed and delivered to a conveyer-which has apredetermined travel to allow the chemical reaction to take place, inwhich themixture changes from a sludge of more or less liquid form tothe integral spongy form.

The present process also contemplates that this spongyintegral mass mabe continuously disintegrated or broken own for continuous delivery tothe curing pile, where the materials remain a sufficient length of timeto permit the chemical reaction to continue. v Another purpose of theprocess is to combine a quantity of ground phosphate rock with the sludgmixture to increase the available phosphoric acid obtained from themixhire.-

The spon y mass contains a certain percenta of ree phosphoric acid whichrenders 1t damp and sticky and unfit for application to the soil in thiscondition, since It would clog and not pass through a drill .or machinefor applying the phosphates to the soil. Another purpose of the presentprocess, therefore, 18 to remove vaporor moisture from the materials asthe spongy mass is disintegrated, so as to render the same insufiiciently dry and pulverent condition for ready application to thesoil.

The process may be practised by the use of various apparatus, but forpurposesof Fig. 2 is a vertical section taken on line 2---2 of Fig. 1;

Fig. 3 on an enlarged scale is a vertical section through a nozzle whichma be employed in mixing the ground phosphate rock and the acid; and

Fig. 4 is a detail of a feed device tobe' referred to. 7

Referring to the drawings, the apparatus MASSACHUSETTS, ASBIGNOB TOS'IURTEVANT MILL shovvfi1 therein as one good form of means by ,w '01;the process may be practlsed, comprises. a hopper 1 which maycontinuously receive the ground or pulverent phosphate 5 rock from anysuitable source of supply, and unnecessary to disclose herein. Th1s h'pper communicates .with a tube 3 contalnmg a feed screw 5 which may bedriven by any suitable means. This means, in the pres- 10 ent instance,com rises a shaft 7 having a ratchet' wheel 9. ast thereon adapted to.be advanced step-by-step by pawls 11 (Fig. 4) carried by the fork 13fulcrumed'on the shaft 7,'and at the upper end of an arm 9 15 connectedbya link 15 with a wrist pin 17 on a wheel 19 mounted on a shaft '21which ma be driven by any suitable means. It is desirable that the feedmay be varied. To accomplish this, in the present instance, the

-20 link 15 is adjustably connected to the arm 9 by a bolt 23 enteredthrou h an elongated slot 25 in the arm 9. By a justing the boltlongitudinally of the slot 25, the range ofrocking movement of the arm 9may be 25 varied, and the speed of rotation of the ratchet may beregulated.

Suitable means ma be prov ded for supplying the acid which is to bemixed with the ground phosphate rock. Th1s means, 80 in the tank 2 (Fig.2) connected by a pipe 29 with a constant level tank 31, a pump 33.

being interposed in the pi 29 for elevating the acid from the supp ytank 27 to the.

. constant level tank 31. An overflow pipe 35 leads from the upper endof the constant level tank 31 back to'the supply tank 27.

The construction is such that the pump will continuously supply acid tothe tank 31,

40 and the acid-will overflow throu h the return'pipe 35. As aconsequence, t e level of 1 the acid inthe tank 31 will automatically bemaintained at-a constant level with 'a constant head. A ipe 37 leadsdownward from the constant evel tank 31 to a point .ad'acent the tube 3.

uitable means may be provided to receive the round phosphate rock fromthe tube 3, and the acld from the constant level 150 tank 31. Thismeans, in the present instance, is'in'the form of a nozzle 39 comprisinga body 41 Fig. 3) having a neck 43 connected to the elivery end of thetube '3. This body contains a tube 45 having its '55 upper endcommunicatin in turn with the acid suppl pipe 37. T e amount of aciddelivered t rough the nozzle may be regulated by a needle valve 49 atthe lower end of a stem 51 threaded intofthe upper end of the body '41andprovided with a hand wheel 53. i

The tube 45 may havefixed spiral vanes 55 therein extending from the topof the tube to themouth 57 at the lower end of the tube. Theconstruction is' such thatas present instance, is in the form of a' theacid passes down throu h, the tube, the

be delivered in distributed or whirling form into the path of the acidspray issuing from the mout 57. As a consequence, the ground phosphaterock and acid will be thoroughl mixed as the are continuously fed througand'delivere from the nozzle. The prop tions of the round phosphaterockand acid may be regu ated by adjustment of the feeding means for therock and the needle valve for the-acid.

As stated, the process of the-present invention contemplates that themixed materials may be fed by a conveyer with a travel sufficient. toenable the chemical reatcion to take place, and to permit the materialsto change from slud e to s ongy mass form. To accomplish this, in bepresent instance, a casing 61 (Figs. 1 and 2) may be provided having achamber 63 adjacent one end thereof into which the nozzle 39 projects.Mounted within the casing is a conveyer, in the present instance in theform .of a trough 65 hich may be made of sections 67 secured to links ofsprocket chains 69 on sprocket wheels 71 and 73 mounted on shafts 75 and77 journaled in bearings on suitable supports 79 adjacent the casing 61.The shaft 5 may have a wheel 81 fast thereon which may be driven fromany suitable source of power.

As stated, the process of the present invention contemplates that aquantity of ground phosphate rock shall be mixed with the sludge mixtureof ground phosphate rock and acid. "To accomplish this, in the with atube 85 containing a feed screw 87 on.

a shaft 89 which may be driven by any suitable means in the presentinstance, com rising a ratchet wheel 91 fast on said s aft, andpawls 93carried by the up er ends of a fork 95 on an arm 97 fulcrumed 89. Thisarm-maybe connected b a link 99 with a wrist -pin 101 on a wlieel 103mounted on a shaft 105 which may be driven b suitable means. Thisdriving means for tli e feed screw 87 ma be similar to that disclosed inFig. 4, an described for drivi the feed screw 5 referred to. An inclineon the shaft plate 107' end of thetube 85 down to the bottom'of thetrough conveyor g a i y The constructionis such that the round phosphaterock may be continuous y fed rom thejhopper 83 by the feed screw 87throughthe tube 85 and downthe inclined plate *107 to the bottom of thetrou h'conveyer. The materials thusintroduce to the conveyor willreceive theslud e mixture and desirabl increase the available phosphoricacid. he fground phosphate rock thus introduced to the bottom of thetrough conveyer will also form a bed in the bottom of the'troughwhichwill. tend to preventleakage of thesludge betweenthe sections of thetrough. I

The sludge which is delivered from the nozzle 39 into the chamber 63will gravitate downward into the trough conveyor, and will becontinuously fed toward the delivery endthereof. vThe length of theconveyer and the speed, thereof may be such that the materials intraveling from the feeding-in end to the delivery end of the conveyerwill experience the chemical reaction which hereto ore has taken placewhile themixture is a standing in the den. In the course of this driesthe same.

travel, the materials will change from sludge to spongy mass form.

T e process of the presentinvention contemplates that this mass shall bedisintegrated on reaching the delivery end of the conveyer. Toaccomplish this, in thepresent instance, a cutter 109 (Fig. 1) may beprovided comprising a hub 111 having curved knives 113 secured thereto,present instance, six such knives being shown. The hub 111 may bemounted fast on a shaft 115 which may be driven by suitable means.

The construction is such that the block or spongy mass will be slowlybut continuously fed to the cutter, and the knives of the latter willcome in contact with the advancing end of the mass and break down ordisintegrate the same. The disintegratedmaterials may be delivered fromthe casing 61 throu h an outlet 117, and may be conveyed there rom byany suitable means to the curing pile, in order that the chemicalreaction may continue and the materials may be in condition for use.

Noxious fumes accompany the chemical reaction taking place as thematerials travel from the feeding-in end to the delivery end ,of theconveyor, and the materials contain steam or moisture which should beremoved. The construction of the cutter is such that not only serves todisintegrate the materials, but also as a blowerto produce a draftof airwhich acts on the materials as they are disintegrated and desirablyaerates and The fumes and steam ma be conveyed from the casing 61-throug in .the

branch chimneys: 119 leadirig to a vmainchimney 121.

screw containing tube 3 to the nozzle 39.

It maybe desirable to'break up thegroimd 1 v rock phosphate as it is fedfrom the feed This may be accomplished by compressed air which may beintroducedinto the tube through a pipe 123 which may receivethecompressed air from a suitable aircomressor unnecessary to be Shownherein.-

he pipe 123 may be provided with a gage 125 to indicate the pressure.The construction is such that after the materi'al's'have been fed by-thefeed screw, the compressed air will act on the materials and preventtheir packing entrance into the nozzle.

In accordance with the process which may be practised by the apparatusdescribed, the ground phosphate rock and the acid, such, for example, assulfuric acid are continuously mixed and continuously fed with a andchoking thetube and the suflicient travel to allow time for the chemicalreaction to take place which converts insoluble phosphoric acid intosoluble phosphosphate .rock is added to the mixture, which furthercontributes to the available phosphoric acid. The spongy mass iscontinuousl disintegrated and aerated, and the materia s are thuscontinuously treated in readiness fordelivery to the curing pile.

It will be understood that various deviations may be made from theprocess described wlthout departing from the spirit and scope of the apended claims.

What is claims is 1. A process for manufacturing acid phosphate,characterized b continuously mixing ground phosphate roe]: and acid,allowing. a chemical reaction to take place to convert the insolublephosphoric acid while conveying the mixture away from the mixer into souble phosphoric acid, and disintegrating the mixture to liberate vaportherefrom.

2. A process for manufacturing acid phosphate, characterized bycontinuously mixing veying the mlxture through a sufiicient travel toallow a chemical reaction to take place to convert insoluble. phosphoricacid into soluble phosphoric acid.

3. A process for manufacturing acid phosphate, characterized bycontinuously mixing ground phosphate rock and acid to form a sludge,combining the sludge with a quantity of ground phosphate rock, andmoving the materials a sufficient length of time to allow the chemicalreaction to take place and convert insoluble phosphoric acid intosoluble phosphoric acid.

4. A phate, characterized by continuously mixing ground phosphate rockand acid to form a sludge,combin1ng the sludge with a quanphoric acid. Acertain' percentage of ground y processfor manufacturing acid phos- Imateria phosphoric aci tity of oupd phos hate rock moving the fi asufiicient ength of tinfe to allow the chemical reaction to take placeand convert-insoluble phosphoric acid into soluble phosphoric acid, andcontinuously disintegatingthe mixture to liberate vapor there-.

5. A process for manufacturing acid phosphate, characterized bycontinuously mixmg ground phosphate rockand acid to form.

a sludge, combining the sludge with a quantity of round phosphate rock,moving the materia s asufiicient length of time to allow 1n oundhosphate rock and acid, continuously mixing the same, continuouslyc0nveyin the mlxture to allow-the same to change rom sludge to spongymass form,

- and continuousl disintegrating the mixture.

7. A process or manufacturing acid phoshate, characterized bycontinuously mixmg ground phosphate rock and acid, regulating theproportions of the mixture, continuously conveying the mixture to allowthe materials to change from slud e to spon mass form, and continuouslyisintegratmg the mixture.

8. A process for'manufacturing acid phosphate, characterized bycontinuousl mixmg ground phosphate rock and aci moving the mixture withsufiicient travel to allow a chemical reaction to take place to convertthe insoluble osphoric acid into soluble phosphoric acig, disintegratingthe mixture and aerating the disintegrated materials.

9.- A process for manufacturing acid phosphate, characterized bycontinuously feedmg ground phosphate rock and acid, introducing air tothe ground phosphate rock to prevent the same from compacting, mixingthe ground phosphate rock and acid to form a slud e, continuously movinthe mixture a sufiiclent length of time to alfiiw the chemical reactionto take lace to convert insoluble phos horic acid 1nto solublephosphoric acid, an disintegrating the mixture-to liberate vaportherefrom.

In testimony whereof I have signed my name to this specification.

. WILLIAM T. DOYLE.

